Blunt trauma reduction fabric for body armor

ABSTRACT

A three-dimensional knit spacer fabric for use in ballistic protective garments is provided. The fabric includes a first fabric layer made from high performance, high tenacity yarns; a second fabric layer of an open mesh construction to facilitate air circulation; and a plurality of high performance monofilament yarns interconnecting the two layers.

RELATED APPLICATIONS

This is a continuation-in-part of application Ser. No. 09/406,183 filedSep. 24, 1999, now abandon which is a continuation of application Ser.No. 09/058,115 filed Apr. 9, 1998, now U.S. Pat. No. 6,103,641.

BACKGROUND OF THE INVENTION

The present invention relates to protective body armor of the soft andhard types designed to resist penetration by bullets, buckshot, pellets,shrapnel or other projectiles.

The main objective here is to provide a fabric capable of significantreduction in the so called “blunt trauma” effect leading to injury ofthe armor's wearer. While the armor stops penetration of the projectile,it allows its kinetic energy to be transferred through the armor systemdirectly to the body of the wearer as to cause injuries to the bonestructure and internal organs.

This injury is described in the protective apparel industry as “blunttrauma”, which is correlated to the extent of inward deformationsuffered by the armor as it is impacted by a projectile.

The armor itself is made from a plurality of layers of ballisticresistant material. The maximum extent of deformation accepted underindustry standards is 1.73 inches as measured in the clay material usedto simulate human flesh impacted by ballistic effect on the armor.

Various devices or materials have been designed to be worn under thebody armor to absorb the impact of a projectile striking it and thusreduce the inward deformation and hence the blunt trauma, which wouldminimize or possibly eliminate any injury to the wearer. Such devicesinvolve the use of foam, non-wovens, plastic honeycombs and othermaterials. Their main drawback is the lack of air permeability, whichcauses the wearer to perspire excessively and leads to avoidance of thebody armor protection despite the hazards involved. In many cases, lawenforcement officers refuse to wear their armor because of the acutediscomfort induced by its impermeable components.

SUMMARY OF THE INVENTION

A three-dimensional knit spacer fabric for use in ballistic protectivegarments is provided. The fabric includes a first fabric layer made fromhigh performance, high tenacity yarns; a second fabric layer of an openmesh construction to facilitate air circulation; and a plurality of highperformance monofilament yarns inter-connecting the two layers.

The main object of the present invention is to provide a highperformance, cost effective blunt trauma reduction fabric system whichis comfortable to wear on account of its air permeability, perspirationabsorptive qualities and pleasing tactile esthetics against the wearer'sbody.

A further objective is to enhance, if required, the projectile stoppingpowers of the body armor as to reduce its thickness and weight.

Another objective is to provide cushioning and impact absorption whenthe wearer is involved in such hazardous situations as vehicle crashes,combat, falling debris, falls, etc., encountered in pursuitperpetrators, storming buildings or hideouts, or dealing with riotsinvolving exposure to stoning or violent crowds.

Yet another objective is to provide a fabric system conforming to thecontours of the wearer's body in a snug, comfortable fit.

Finally, it is an objective to provide fabric which may be washed, ordry cleaned, while offering long term durability.

Still other objects and advantages of the invention will in part beobvious, and in part apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the spacer fabric of the invention;

FIG. 2 is a side view in cross-section of a potion of body armorincorporating the inventive spacer fabric.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The fabric involved in the present invention is known in the industry as“Spacer” fabric because its components are spaced widely apart as tocreate a 3-dimensional structure. The fabric is made on a warp knitbasis, preferably on a two needle bar specialty Raschel machine. Thefabric may also be made on weft knit circular machines of the rib orinterlock type.

The schematic structure of the Raschel type spacer is illustrated onFIG. 1. Fabric 1 comprises two component webs or layers, namely frontface 2 and back face 3. Back face 3 is attached to front face 2 by asystem of interconnecting yarns 5 filling the interval or distancebetween the faces. This distance may be set from 12 to 30 millimetersdepending on product requirements as far as impact absorption isconcerned. This arrangement also permits free air circulation, thussignificantly enhancing the comfort factor of the system.

Yarns 5 are preferably monofilament in order to increase resilience,including those of the bi or multi-component fiber type, and have afineness of 70-200 denier. The higher their denier, the greater theresistance to deformation under the influence of impact. The sameapplies to the density of the threads per square inch in the fabric.This density may be varied by suitable guide bar threading, machinegauge, knitting tightness, the number of guide bars carrying thosethreads and the knitting construction used to generate each of thefabric faces. The density ranges from 1,000-3,000 threads/sq. inch. Theinterconnecting yarns also have a substantial stiffness in the range of30-90 based upon the industrially known Shore A scale. Theinterconnecting yarns are selected from high performance yarns, asdescribed below, having a tenacity of at least 15 gram/denier.

Faces 2 and 3 are knit independently of each other by their own set ofguide bars, a technique well known to those skilled in the art. Thispermits making each face from a different knitting construction andusing different yarn types and deniers, if required. For example, backface 3, placed against the wearer's body, may be made from hightenacity, high filament count polyester yarns (70-300 denier) forsoftness and moisture absorption, while front face 2 is made from highperformance yarns designed to resist penetration of projectiles orshrapnel. Yarns of front face 2 should also have a tenacity of at least15 gram/denier.

Fabric 1 of the invention may be incorporated into body armor 9 (seeFIG. 2) that is used in ballistic protection garments. Armor 9 includesa plurality of textile layers or plies 8 for defining an armor portion7. Armor portion 7 is separated from spacer fabric 1 by a fabric layer13. Armor 9 is enclosed in a fabric wrap 15. Textile layers 8 are madefrom non-wovens, wovens, ceramic or plastic panels, steel plates, etc.,as is well known.

Construction of back face 3 may be in an open or mesh form (porous) foroptimum air circulation, while front face 2 may be of a solid and heavyconstruction in order to stop projectiles should they or their splinterspenetrate the protective layers of the body armor itself. Specifically,front face 2 comprises a fabric layer with yarns configured into loopswith or without inlays made from ground yarns and inlay yarns. Theknitting method may involve inlay yarns disposed substantially straightor diagonally in the fabric layer defining front face 2. Disposal of theyarns is preferably straight for optimum structural stability.

Optionally, the yarns of back face 3 are made of polyester yarns thathave been rendered hydrophilic in order to enhance transport of bodyfluids (i.e., capillary action), and thereby keep the skin surface dry.

Also, each of the face fabrics may be made in different weights,thickness, porosity, degree of stability and other physicalcharacteristics to suit the purpose of providing optimum blunt traumaprotection combined with enhanced splinter stopping performance.

Such spacer products provide a very effective blunt trauma reducingmedium, while protecting against residual projectile or shrapnelpenetration, as well as imparting the system with good wearing comfort.

In particular, when combining the inventive three-dimensional knitspacer fabric with conventional ballistic resistant material, the extentof deformation will have an improvement of at least 5-10% for generalstreet type handgun uses.

The stitch design, fabric parameters and yarn selection must becarefully chosen in order to ensure maximum projectile, shrapnel orsplinter stopping power while maintaining optimum comfort qualities. Forexample, if the fabric is knit too open to enhance its breathability,there will be a risk of a projectile or splinter penetrating through itsstitches and interstices. Yet, if it is knit too tightly, the fabric isimpermeable to air, it is hot and is uncomfortable to wear. Therefore, aright balance between all the fabric requirements must be achieved byselecting the appropriate parameters and design for the fabric. Animportant consideration here is the degree of risk to the wearer of thebody armor in terms of the type, weight and velocity of the projectilethe armor is expected to stop.

Ballistic tests have shown that suitably designed spacers cansignificantly reduce the number of fabric plies in the armor itself forany given projectile protection level. This lowers armor weight and costwhile improving overall comfort to the wearer.

The choice of yarns depends on the type of armor used for a specificpurpose, which in turn is predicated on the velocity of firearmprojectiles liable to be encountered by the wearer. This has beenspecified by the NIJ (National Institute of Justice) Standard 010103,which divides bullets into 6 classifications depending on the velocityand weight (4 for handguns and 2 for rifles).

In order to impart the fabric with improved ballistic properties, highperformance, high tenacity yarns must be used on the front or even bothfabric faces, depending on the degree of hazard and type of bullets thearmor wearer may encounter.

The designation “high performance” applies to yarns with a tenacitygreater than 15 gram/denier, with yarn modulus of 500-2,000 gram/denier,which includes such fibers trademarked as DuPont's “Kevlar,” AKZO's“Twaron,” Teijin's “Technora,” all in the Para-Aramid group;Allied-Signal's “Spectra” and the DSM-Toyobo's “Dyneema” in the ultrahigh molecular weight polyethylene group; and the Hoechst-Celanese's“Vectran,” a liquid crystal polymer based fabric and Toyobo's PBO fiberknown as “Zylon.”

An example of fabric construction with one face in Kevlar and another ofhigh tenacity polyester is knitted as follows:

Bar 1 (front) 400 den Kevlar, knit 10-10-10-0/0-0-0-10 Bar 2 400 denKevlar, knit 0-2-2-2/2-0-0-0 Bar 3 80/1 den Polyester 0-2-2-2/2-0-2-0Bar 4 80/1 den Polyester as bar 3 Bar 5 500 den Polyester0-0-0-2/2-2-2-0 Bar 6 500 den Polyester 0-10-10-10/10-0-0-0 Machinegauge - 12-20 needles/inch. Trick plate spacing 14 millimeter.

Another suitable structure is described by the following example:

Bar 1 (front) 650 den Spectra knit 2-0-2-2/4-6-4-4 Bar 2 650 den Spectra4-2-2-2/0-2-2-2 Bar 3 80/2 den Polyester 2-0-6-4/8-10-4-6 Bar 4 80/2 denPolyester 6-4-2-0/4-6-8-10 Bar 5 400 den Kevlar 2-2-4-2/2-2-0-2 Bar 6400 den Kevlar 4-4-2-0/2-2-4-6 Trick plate spacing-16 mm

Spectra is a high modulus polyethylene fiber of very high tenacity, madeby the Allied-Signal Corp.

It will be noticed that the above fabric is knit with each of its facesembodying different yarn systems. Thus, one face is in 650 den Spectra,while the other in 400 den Kevlar. This structure has been selected inorder to take advantage of the specific porperties of each of thesefibers so that their combined effect enhances the performance of thefabric.

Of course, the above fabrics are just two examples of the manyconstruction options based on such variables such as fiber type, denierand filament type, knitting pattern, machine gauge and trick platespacing. Such options are well known to those skilled in knitting arts.

A weft knit spacer fabric of a similar character may be constructed onthe same principle using rib or interlock machines fitted to carry outthe operation of knitting, tucking and missing and a provision to set asuitable distance between the cylinder and dial. Both dial and cylinderknit independently their own fabric faces, which are joined into aspacer product with a monofilament yarn.

The spacer fabric of the invention is suitably constructed to constitutea significant improvement over other ballistic impact absorption systemssuch as foam, honeycomb, non-woven and other materials heretofore usedas blunt trauma reduction mediums.

The advantages of the inventive spacer fabric system over otherscurrently used in the field are:

1) Reduction in the number of plies or layers of fabric in the armor orvest, which lowers its weight and price and enhances wearing comfort.

2) Added ballistic protection, especially from bullet splinters orshrapnel. This is due to the two layers of the spacer fabric providingan extra penetration resisting barrier.

3) Permeability to air. The facility to conduct away the perspirationfrom the skin surface greatly contributes to wearing comfort.

4) Pleasant tactile characteristics. The face of the spacer, because ofits textile nature, is more compatible with skin than foam or otherplastic materials.

5) Hygienic considerations. The spacer, as a textile product, is mucheasier to keep clean through washing or other means than such materialsas foam, honeycomb, etc.

6) Shape conformance. The knit character of the spacer makes it conformto the body contours better than other materials.

7) Long term resiliency. The “cushion” effect of the spacer does notdiminish with age or use, unlike with foam or other materials.

8) Ecologically friendly. Spacer fabrics may be recycled throughchemical means, unlike with foam, which cannot be recovered or degradedin landfills.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained by thepractice of the subject invention.

I claim:
 1. A three-dimensional knit spacer fabric for use in ballisticprotective garments comprising a first fabric layer made from highperformance yarns of a tenacity of at least 15 gram/denier; a secondfabric layer of an open mesh form to facilitate air circulation and toenhance wearing comfort by allowing freedom of movement and conformingto body contours; and a plurality of monofilament yarns interconnectingsaid first and second layers having a fineness of 70-200 denier, whereinsaid plurality of interconnecting yarns have a length extending betweensaid layers that substantially corresponds to the distance between saidlayers.
 2. The fabric of claim 1, wherein said layers are spaced adistance from between about 12 and 30 millimeters.
 3. The fabric ofclaim 1, wherein interconnecting yarns have a density of between about1,000 and 3,000 threads/sq. inch.
 4. The fabric of claim 1, wherein saidfirst fabric layer yarns comprise inlay yarns disposed substantiallystraight.
 5. The fabric of claim 1, wherein said second fabric layer ismade from polyester yarns.
 6. The fabric of claim 5 wherein saidpolyester yarns have been rendered hydrophilic.
 7. The fabric of claim1, wherein said interconnecting yarns are made form high performanceyarns of a tenacity of at least 15 gram/denier.
 8. A three-dimensionalknit spacer fabric for use in ballistic protective garments comprising afirst fabric layer made from high performance yarns of a tenacity of atleast 15 gram/denier, said high performance yarns being knit to impartsaid first fabric layer with ballistic properties selected to resistpenetration by high velocity projectiles; a second fabric layer of anopen mesh form to facilitate air circulation and to enhance wearingcomfort by allowing freedom of movement and conforming to body contours;and a plurality of yarns interconnecting said first and second layers,wherein said plurality of interconnecting yarns have a length extendingbetween said layers that substantially corresponds to the distancebetween said layers.
 9. The fabric of claim 8 where said highperformance yarns have a yarn modulus of 500-2,000 grams/denier.
 10. Thefabric of claim 8 where said yarns interconnecting said layers have afineness of 70-200 denier.
 11. A three dimensional knit spacer fabriccomprising: a first fabric layer, a second fabric layer; and a pluralityof interconnecting yarns arranged and constructed to maintain said firstand second fabric layers at a predetermined distance from each other; atleast one of said first and second fabric layers being knit from highperformance yarn in an arrangement selected to intercept and provideprotection from high velocity firearm projectiles.
 12. The threedimensional fabric of claim 11 wherein said high performance yarns havea tenacity of at least 15 grams/denier.
 13. The three dimensional fabricof claim 11 wherein said high performance yarns have a yarn modulus of500-2000 grams/denier.
 14. The three dimensional fabric of claim 11wherein said first layer is adapted to intercept high velocityprojectiles and said second layer is formed from yarns knit to allowhigh air circulation.
 15. The three dimensional fabric of claim 11wherein said first and said second layers are knit from yarns arrangedin a pattern selected to intercept high velocity projectiles from firearms.
 16. The three dimensional fabric of claim 11 wherein said layersare spaced a distance from between about 12 and 30 millimeters.
 17. Thethree dimensional fabric of claim 11 wherein interconnecting yarns havea density of between about 1,000 and 3,000 threads/sq. inch.
 18. Thethree dimensional fabric of claim 11 wherein said first fabric layeryarns comprise inlay yarns disposed substantially straight.
 19. Thethree dimensional fabric of claim 11 wherein said second fabric layer ismade from polyester yarns.